A rear diffusor is an aerodynamic element on the lower side of a vehicle body in the region of a rear of a vehicle. The rear diffusor is customarily movable here in such a manner that its angle and/or its distance with respect to a carriageway surface can be changed. As a result, a force is exerted on the vehicle by means of an airflow which flows on a lower side of the vehicle. It is therefore possible, by means of the rear diffusor, to influence the driving performance of the motor vehicle in respect of the vehicle down force and the aerodynamic drag.
In this connection, a vehicle with an air-directing device is known, for example, from DE 10 2011 103 787 A1. On a lower-side rear region at the rear behind the rear wheels, the vehicle comprises a body-mounted base. The air-directing device is fastened to the body-mounted base and comprises a directing element which extends in the transverse direction of the vehicle and is adjustable between an inoperative position and an operating position by means of an actuating mechanism.
Furthermore, DE 10 2013 105 842 A1 discloses a particularly advantageous motor vehicle with a rear diffusor. A diffusor is arranged at the rear of the motor vehicle in the region of the underbody, the diffusor having a front fixed diffusor part of the underbody and an adjoining, downwardly foldable rear diffusor end part of the underbody. The diffusor end part can also be composed of a separate element and placed onto the underbody. By displacement of said diffusor end part into an upwardly folded position and into a downwardly folded position, down force/lift effects and aerodynamic drag effects are appropriately obtained.